1. Are you viewing HTML format mail which is setting colors? 2. Does one (or more) of these bug reports https://mzl.la/2ZNsyD6 match your issue ?

Hi Wayne -

The current problem is that I was using a customized dark mode throughout my Windows 1O platform.

The upgrade (and reinstall to 78) left my message reading pane dark with white text and other email that contains HTML is also dark (see above pictures that I have posted) - same for message composition pane.

In Bugzilla, there are indications of the same or similar problem. Perhaps you can point to this thread in Bugzilla so that Mozilla has a idea of what I am attempting to convey here.

The update to 78.0.1 did not correct the problem.

Thanks for your help!

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Hello Wayne -

1. Are you viewing HTML format mail which is setting colors? 2. Does one (or more) of these bug reports https://mzl.la/2ZNsyD6 match your issue ?

Bugzilla has a few entries that are similar to my situation. See my pictures above.

I'm running Windows 10 with Classic Shell and adjusted the colors in Personalization for Dark Mode. I also checked off the following boxes:

Show accent color on the following surfaces:

Start, Taskbar and Action Center Title bars and Windows borders

Everything in TB was forking *perfectly* until the 78 upgrade. Even the new 78.0.1 did not fix it.

My message pane where I read my messages has a dark grey background with white text. The message composition pane has the same issue.

Tried reinstalling TB 78 without any effect.

Even used the default them for TB - only changing it to light resolves the issue - but it also changes the Action Center and other W10 windows to light as well. Right now I am using the default theme.

HTH.

Hi again.

Is there a bug status on this?

TIA :)

OK. Currently my 68.10.0 has not offered an update, so I decided to install 78.0.1 to another drive and run both symultaneously to appreciate the issues you are all discussing.

Oh dear. I now fully understanding what a complete mess this appears to be. I now get the picture and can understand why there is so much frustration.

Windows 10: I'm using System Dark Mode enabled on computer and default app mode is also dark. Thunderbird is set to default Light Mode and all the following is based on that Thundrbird setting.

However, in Thunderbird 78, the only part that is Light mode is Address Book, Calendar, Folder Pane, Thread Pane and drop down menus. Also 'Write window except the area where you compose.

Everything else is as if dark mode.

• Troubleshooting Information, Options, Addons, about:Profiles, about:config, composing area in Write window

This background is directly controlled by the computer default app mode being dark. Changing the computer default app mode to Light alters the background to white.

Message Pane is being controlled by various sources.

• Test: 'View' > 'Message Body as' > 'Plain text' or 'Simple HTML
• The background is dark grey almost blackish - and my blue font colour is used. (TB Safe mode - font colour is white if app mode dark and font colour is controlled by Options > General 'Fonts & colours' > Colours - Text).

This background is directly controlled by the computer default app mode being dark. Changing the computer default app mode to Light alters the background to white.

• Test: 'View' > 'Message Body as' > 'Original HTML'

If person sent email in plain text only, then those emails will have the dark grey or white background depending upon the computer default app mode.

Emails with HTML css that controls the background eg: emails from this support forum or Facebook are pale background by design But that background can be completely controlled by HTML css created by sender. However, much of the font colour of standard text can be controlled by the Options > General > 'Fonts & colours' > Colours - Text colour providing you are using computer app mode light. If using app mode dark then you can discover white font is being forced by computer app mode choice onto a background controlled by email html eg: white on white.

In Options > 'Composition' 'Use Readers default colours' uses whatever has been set in Options > General > 'Fonts & colours' > Colours - Text colour .

When composing a new email in Plain Text: Font colour is not controlled by the section 'Plain Text Messages'.

Conclusion: Computer app mode influences many areas of Thunderbird.

Emails with HTML can control the background.

Options > General > 'Fonts & colours' > Colours - Text colour can control font colour if using app mode light with Thunderbird Light mode.

Thunderbird Dark Mode seems to have less issues on readibility of emails in Message Pane, but will still cause various areas to act like they are using Light mode - same as vice versa.

@Toad-Hall -

Well, I'm glad that you see what I am speaking about. Question is, when will Mozilla fix this mess, lol.

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The folder issue should be fixed in 78.1. The odds of fixing the HTML issue in 78.1 are extremely low. But it is an identified issue that someone is researching.

The folder issue should be fixed in 78.1. The odds of fixing the HTML issue in 78.1 are extremely low. But it is an identified issue that someone is researching.

Thanks, Wayne -

I'm a bit surprised that this problem was not detected in testing. Some of my incoming HTML mails are so dark that I have to forward them to another email client to display.

It's a double sided sword -

If I touch the "Dark Mode" setting in Windows 10, then the desktop is way too bright. Thunderbird is the only application affected.

Cheers. :)

I am running TB 78.0.1 and have a couple of issues with it so far.

Firstly when you open TB and it shows the Account Settings screen for your email account, the writing is blurred, see attachment.

The second issue I have found is that when using the colour palate in the Properties section to change the Icon colour for the folder, if you create a custom colour and then Add to Custom Colours, you can only do this once as the second time you Add to Custom Colours it overwrites your first custom colour, so you can only ever have 1 custom colour!

You may want to adjust the ClearType font settings is it's a Windows PC. The attached picture doesn't seem blurry, but the font size and color is a poor choice.

You can have several custom colors, as long as you add them all at the same time, as they will be overwritten if the window is closed and reopened. Worse, the custom colors are not retained between TB restarts.

As a heads up info.....

I've checked the source code and now understand why some emails with a dark background and dark text occur.

Thunderbird dark mode, computer app mode dark

Emails can seem unreadible as background is dark with dark text !

Problem identified: It occurs if the sender of email says html css dictates the style = font colour as a dark colour and they have set style background color to 'transparent'. No problem if the style background color is set as eg: white.

So this explains what is causing the problem in this instance. I've reported it to the bug report that is looking into why some emails are not readible when using dark mode.

As a heads up info..... I've checked the source code and now understand why some emails with a dark background and dark text occur. Thunderbird dark mode, computer app mode dark Emails can seem unreadible as background is dark with dark text ! Problem identified: It occurs if the sender of email says html css dictates the style = font colour as a dark colour and they have set style background color to 'transparent'. No problem if the style background color is set as eg: white. So this explains what is causing the problem in this instance. I've reported it to the bug report that is looking into why some emails are not readible when using dark mode.

OK. However, what about the Dark Background in the compose and reading panes without any text?

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Wayne Mery said

The folder issue should be fixed in 78.1. The odds of fixing the HTML issue in 78.1 are extremely low. But it is an identified issue that someone is researching.

Thanks, Wayne -

I'm a bit surprised that this problem was not detected in testing. Some of my incoming HTML mails are so dark that I have to forward them to another email client to display.

Apparently not enough people using dark mode. But more testers like yourself would make that possible. Everyone is welcome.

Whilst the bug people are working on this problem, I suggest you try the information below to help with the situation. If computer app mode = dark and using dark mode in Thunderbird, the following will force a light mode onto the Message Pane and a few other areas. But it does mean you can keep app dark mode for computer apps and use dark mode in Thunderbird and see all emails.

• Menu app icon > Options > General
• scroll to the bottom and click on 'Config Editor' button

It will say be careful

• right click in the list of preferences area and select 'New' > 'Integer'
• At prompt enter the preference name: ui.systemUsesDarkTheme
• click on OK
• Enter the Value: 0
• click on OK

• Close 'about:config' - top right x

I had a similar problem (unreadable white text on white background or black text on black background in received emails) with Thunderbird 78.0.1 (64-bit) on up-to-date Windows 10. Windows 10 is set to dark mode.

I was able to mitigate the symptoms of this bug as follows:

1. Open the Config Editor ( Tools > Options > General > [scroll to the very bottom] > Config Editor )
2. Add new integer value ( [right click the list] > New > Integer )
3. Name the value ui.systemUsesDarkTheme
4. Set the contents of the value to 0
5. All emails should now be readable again, but Thunderbird's default theme reverts to a light one.
6. If preferring the dark theme, go to the Themes menu ( Tools > Add-ons > Themes ) and manually enable the "Dark" theme; this will restore "some" parts of the UI back to dark mode. Unfortunately, many things such as the Options and Add-ons menus themselves are not affected by this.

Clearly, something is fundamentally broken with how Thunderbird decides what parts of the UI should be affected by dark/light mode.

Expected behavior:

• The OS dark/light setting should have no effect whatsoever on Thunderbird, unless the default theme is active.
• All parts of Thunderbird's UI should be affected by which theme is active.
• Emails that are not plaintext should never be affected by any form of dark mode.

Observed behavior:

• The OS dark/light setting directly controls multiple parts of Thunderbird's UI, regardless of which theme is active, including HTML formatted emails.
• Several parts of Thunderbird's UI are not affected by the active theme, e.g. the options menu.
• HTML formatted emails have their default color values replaced by the OS dark/light setting, rendering them potentially unreadable (e.g. white text on white background or black text on black background).

While the above steps do mitigate the impact of this bug, I hope the root cause of this bug will be resolved soonish.

re :HTML formatted emails have their default color values replaced by the OS dark/light setting, rendering them potentially unreadable (e.g. white text on white background or black text on black background).

I have established that in these instances, the received email html css style was using background colour set as transparent, so basically not setting anything and using whatever the user had set as default - which depended on users choice of dark or light app mode. However, the emails did control the font colour.

So if the default background was black and the sender enforced a black font then you could not read the emails. Similar issue with with on white. If sender had included a background colour as well as setting the font colour then all emails are perfectly ok. Or if they had not set any font colour then the default would be used and therefore still visible. So, the problem is not as simple as you would hope.

The devs are curently working on a solution.

re :HTML formatted emails have their default color values replaced by the OS dark/light setting, rendering them potentially unreadable (e.g. white text on white background or black text on black background). I have established that in these instances, the received email html css style was using background colour set as transparent, so basically not setting anything and using whatever the user had set as default - which depended on users choice of dark or light app mode. However, the emails did control the font colour. So if the default background was black and the sender enforced a black font then you could not read the emails. Similar issue with with on white. If sender had included a background colour as well as setting the font colour then all emails are perfectly ok. Or if they had not set any font colour then the default would be used and therefore still visible. So, the problem is not as simple as you would hope. The devs are curently working on a solution.

In my specific case, the OS dark/light mode affected the font color, not the background color, turning originally black-on-white mails into white-on-white mails. Either way, it messes with colors where it shouldn't.

Well...

I just installed W10 2004 and dis not select any theme and/or color aside from the Windows Default. Then I installed TB 78 and all was well.

Then I set the system theme to Dark in Personalization -> Colors (choose your color) -> Dark. That was it. Then I also checked off Show Accent Color on the Following Surfaces - both boxes. Same result.

Then I unclicked Dark under Colors and it went away. The remaining two boxes for Accent Color did not make a difference.

Hope this helps you.

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You may want to adjust the ClearType font settings is it's a Windows PC. The attached picture doesn't seem blurry, but the font size and color is a poor choice. You can have several custom colors, as long as you add them all at the same time, as they will be overwritten if the window is closed and reopened. Worse, the custom colors are not retained between TB restarts.

I have looked at the Options in Thunderbird but I can't see anything relating to ClearType font so can you tell me where I can find these settings to change them and what are your settings as your picture was clear and exactly what I am trying to get.

Thanks.

sfhowes said

You may want to adjust the ClearType font settings is it's a Windows PC. The attached picture doesn't seem blurry, but the font size and color is a poor choice. You can have several custom colors, as long as you add them all at the same time, as they will be overwritten if the window is closed and reopened. Worse, the custom colors are not retained between TB restarts.

I have looked at the Options in Thunderbird but I can't see anything relating to ClearType font so can you tell me where I can find these settings to change them and what are your settings as your picture was clear and exactly what I am trying to get.

Thanks.

I found an Adjust ClearType text function in Windows which I ran and then restarted my laptop but the blurry parts in my picture are still the same and nothing like the sharpness that your picture has!

The blurry text is due to a non-default theme (see pictures).